U.S. President Donald Trump is reported to have directed his attorney to lie to Congress about efforts to build a Trump Tower in Moscow.

The late Thursday account on BuzzFeed News said two anonymous federal law enforcement officials were the sources for the report about the president and his former lawyer Michael Cohen.

The sources say Cohen told special counsel Robert Mueller that the president told him to lie to Congress about Trumps dealings with Russia.

BuzzFeed says the anonymous officials are also involved in an investigation of the matter.

According to the BuzzFeed account, Trump and two of his children, Ivanka and Donald Jr., received regular, detailed updates about the real estate development from Cohen, whom they put in charge of the project.

Russia negotiations

At the same time Cohen was providing the Trumps with news about the negotiations with Russia, Trump was engaged in his successful presidential election and denying that he had any business deals with Russia.

The allegation that the president of the United States may have suborned perjury before our committee in an effort to curtail the investigation and cover up his business deals with Russia is among the most serious to date Representative Adam Schiff of California said via Twitter. We will do whats necessary to find out if its true.

Representative Joaquin Castro of Texas posted on Twitter that if the BuzzFeed story is true, then Trump must resign or be impeached.

BuzzFeed says it learned about Trumps effort to have Cohen lie to Congress through interviews with multiple witnesses from the Trump Organization and internal company emails, text messages, and a cache of other documents.

Giuliani on collusion

Meanwhile, Rudy Giuliani, one of Trumps lawyers, has acknowledged that some officials with Trumps 2016 campaign may have colluded with Russia to help him win, but says that Trump himself did not.

I never said there was no collusion between the campaign, or between people in the campaign, Giuliani, a former New York mayor, told CNN late Wednesday.

I said the president of the United States, he added. There is not a single bit of evidence the president of the United States committed the only crime you can commit here, conspiring with the Russians to hack the opposition Democratic National Committee.

On Thursday, Giuliani sought to clarify his remarks, saying, I represent only President Trump not the Trump campaign. There was no collusion by President Trump in any way, shape or form. Likewise, I have no knowledge of any collusion by any of the thousands of people who worked on the campaign.

Giulianis comments during the CNN interview about Trump campaign involvement with Moscow were sharply at odds with what Trump himself has tweeted at least 13 times, that his successful campaign for the White House did not collude with Russia.

Most recently, last month, Trump said on Twitter:

Russia has rejected the conclusion of the U.S. intelligence community that Moscows agents meddled in the election to help Trump win, although President Vladimir Putin acknowledged at last Julys Helsinki summit with Trump that he wanted the then-real estate mogul to defeat his Democratic challenger, former U.S. Secretary of State Hillary Clinton.

Special Counsel Robert Mueller and his team of prosecutors have been investigating Trump campaign links to Russia for 20 months and also whether Trump, as president, obstructed justice by trying to thwart the probe.